Wilson Araújo Lopes

Biodiesel: an overview

The importance of biodiesel production was analyzed based on scientific articles and patents. A critical analysis was presented on the most used oil sources, the catalysts and the methods to verify the transesterification yields. Also analyzed were the comparative studies on emissions from pure fossil diesel and mixtures with biodiesel in variable proportions. Finally some challenges and considerations focused on technological, agronomic and infrastructure aspects of biodiesel production were indicated.

Esquema para interpretação de espectros de substâncias orgânicas na região do infravermelho

This article decribes a simple and systematic method to interpret an infrared spectrum using a flow chart to elucidate the structure of a simple organic compound. It is aimed at undergraduate courses of organic chemistry to make beginners proficient. The proposed flow chart for infrared spectrum interpretation and characterization of organic compounds is suitable for theoretical and experimental courses.

Quantification and source identification of atmospheric particulate polycyclic aromatic hydrocarbons and their dry deposition fluxes at three sites in Salvador Basin, Brazil, impacted by mobile and stationary sources

The present work has aimed to determine the 16 US EPA priority PAH atmospheric particulate matter levels present in three sites around Salvador, Bahia: (i) Lapa bus station, strongly impacted by heavy-duty diesel vehicles; (ii) Aratu harbor, impacted by an intense movement of goods, and (iii) Bananeira village on Mare Island, a non vehicle-influenced site with activities such as handcraft work and fisheries. Results indicated that BbF (0.130-6.85 ng m-3) is the PAH with highest concentration in samples from Aratu harbor and Bananeira and CRY (0.075-6.85 ng m-3) presented higher concentrations at Lapa station. PAH sources from studied sites were mainly of anthropogenic origin such as gasoline-fueled light-duty vehicles and diesel-fueled heavy-duty vehicles, discharges in the port, diesel burning from ships, dust ressuspension, indoor soot from cooking, and coal and wood combustion for energy production.

Multivariate optimization of a GC–MS method for determination of sixteen priority polycyclic aromatic hydrocarbons in environmental samples

This paper describes the development and optimization, by using multivariate analysis, of a GC-MS-SIM method for evaluation of the 16 polyaromatic hydrocarbons considered as priority pollutants in atmospheric particulate material by the US EPA. In order to assure an adequate separation in the shortest analysis time, a multivariate design was used to set the conditions of the oven temperature program. The optimization process was carried out using factorial fractional design and Box-Behnken design. The following factors were evaluated: initial temperature, temperature rate #1, intermediary temperature, temperature rate #2, and final temperature. The optimized conditions were set at: 70 degrees C (2 min) --> 200 degrees C (30 degrees C/min, 5 min) --> 300 degrees C (5 degrees C/min, 1.67 min). Moreover, we have also optimized the injector temperature as 310 degrees C and sampling time as 0.8 min. The total analysis time was 33 min. Validation of GC-MS-SIM yielded satisfactory results for repetitivity of the detector response and retention times, and linearity of calibration curves. LOD were established as 0.13-0.34 ng/mL (peak area) and 0.18-0.72 ng/mL (peak height). The method has been shown to be appropriate for the analysis of samples of atmospheric particulate material and/or other environmental matrices.

Electrochemical reduction potentials of 1-nitropyrene, 9-nitroanthracene, 6-nitrochrysene and 3-nitrofluoranthene and their correlation with direct-acting mutagenicities

In this work, we report measured electrochemical half-wave reduction potentials of 3-nitrofluoranthene (3-NF), 1-nitropyrene (1-NP), 6-nitrochrysene (6-NC) and 9-nitroanthracene (9-NA): = -0.51V; -0.61V; -0.64V; and -0.84V respectively. The cyclic voltammetry experiments with the nitro-PAH were carried out in anhydrous N,N-dimethylformamide (DMF), containing 0.1 mol L-1 tetraethylammonium perchlorate (TEAP) using a three-compartment cell fitted with Pt working and auxiliary electrodes, and a Ag/AgI reference electrode (a silver wire in 0.1 mol L-1 DMF/TEAP containing 0.05 mol L-1 tetrabutylammonium iodide). These potentials can be ordered from the less to the more negative value, which corresponds to the same order by which the direct-acting mutagenicity decreases (3-NF >> 1-NP > 6-NC >> 9-NA). Thus, 3-NF, which shows the less negative first half-wave potential value is the more active mutagenic amongst the nitro-PAH studied. In this way, these properties may be used as an indicative of the health risks, asociated to nitro-PAH exposure, and thus being of great importance in toxicological studies.

Solubilidade das substâncias orgânicas

The solubility of organic compounds is a topic of great importance in chemistry and of interest in several areas, such as materials, drugs and the environment. In this paper, the solubility of these species is discussed in terms of their properties, such as the predominant type of chemical bond, molecular structure, polarity and types of intermolecular interactions. Examples of biological processes fundamental for sustainability of life and related with the solubility of chemical species are presented and discussed.

Bromofenóis simples relacionados ao "flavor" de organismos marinhos

The perception of the flavor is an important attribute of quality in marine fish and other seafoods, being the first and main factor of discrimination for the evaluation, later acceptance and preference of the product by the consumer. Recently, the simple bromophenols have been considered an important group of key flavor compounds occurring in a wide variety of seafood species like fishes, mollusks, crustaceans and algae. When present in high concentration, in seafood, the bromophenols produce an undesirable flavor and are associated with inferior quality. Meanwhile, when present in low concentration levels (for example ng g-1) these compounds produce a desirable marine - or ocean-like - flavor and enhance the existing flavor in seafood. Indeed, simple bromophenols are widespread in seafood but virtually absent in freshwater fish. Herein we present a review on these flavor components found in the marine environment.

Phytomedicinal Studies of Kurram Agency in the Federally Administered Tribal Areas (FATA) of Pakistan

Wahid Hussain, Javid Hussain, Roshan Ali, Sajid Hussain,Muhammad Ashfaq Khan, Ikhtiar Khan, Zabta khan Shinwari, Wilson Araujo Lopes and Iracema Andrade Nascimento Department of Plant Sciences, Kohat University of Science and Technology, Kohat, Pakistan LABIOMAR, Institute of Biology, Campus Ondina, Federal University of Bahia, Brazil. Institute of Basic Medical Science, Department of Biochemistry, Khyber Medical University, KPK, Pakistan. Department of Pharmacy Havelian Campus Hazara Univerisity,Pakistan. Department of Environmental Sciences COMSATS Institute Abbotabad, Pakistan. Department of Plant Sciences,Quaid-i-Azem Univerity Islamabad,Pakistan. 7 Institute of Chemical Sciences University of Peshawar, Pakistan. Institute of Chemistry, Campus Ondina, Federal University of Bahia, Brazil.

Fontes, formação, reatividade e determinação de quinonas na atmosfera

Quinones are a group of semi-volatile organic substances, ubiquitous in nature, belonging to the class of oxygenated polycyclic aromatic hydrocarbons (Oxygenated PAH). These compounds are formed in biogenic processes, through the oxidative metabolism of endogenous compounds, such as catecholamines, estrogen hormones and xenobiotics, as well as directly emitted to the atmosphere, through the incomplete combustion of organic matter, especially the fossil fuels. Additionally, the quinones are formed in the atmosphere by photooxidation of Polycyclic Aromatic Hydrocarbons (PAH). Their reduction products (semiquinones and hydroquinones) are of toxicological interest, due to their ability in generate reactive oxygen species, which may cause damage to membranes, proteins and DNA and, among others damages, may lead to carcinogenesis and induce apoptosis. The most frequently used analytical methods for quantification of quinones in the atmosphere, either in its original form or as derivatized compounds, are high-performance liquid chromatography coupled to mass spectrometry (HPLC-MS) and gas chromatography coupled to mass spectrometry (GC-MS). This review aims to highlight the chemical properties of 1,2-naphthoquinone, 1,4-naphthoquinone, 1,4-benzoquinone, 9,10-phenanthraquinone and 9,10-anthraquinone, the more volatile, reactive and abundant quinones in the atmosphere, as well as the methods usually employed for their determination.

Immediate differentiation of unusual seed oils by easy ambient sonic-spray ionization mass spectrometry and chemometric analysis

Vegetable oils have gained continuous economic importance being increasingly used as renewable raw materials by the food, cosmetics and biofuel industries. As an alternative to the traditional sources of oils, unusual vegetable oils from Jatropha curcas, Bombacopsis glabra, Capparis flexuosa, Siparuna guianensis, Moringa oleifera, Hibiscus tiliaceus, Virola bicuhyba, Pouteria caimito and Syagrus coronata seeds are used. We describe herein the immediate as well as direct, fast and low cost characterization of such seed oils via triacylglycerol (TAG) and free fatty acid (FFA) profiles by easy ambient sonic-spray ionization mass spectrometry (EASI-MS) and chemometric analysis. The oils are shown to display indeed typical and unique chemical profiles of triacylglycerol (TAG) and free fatty acids (FFA) with contrasting carbon lengths, degree of unsaturation or with the presence of other chemical functions on the alkyl chain. V. bicuhyba and S. coronata seed oils were found to be constituted of relatively short chain TAG making them potential raw materials for obtaining biogasolines or biokeresones, which are used as aviation fuels. The TAG profiles of H. tiliaceus were very similar to those of soybean, P. caimito similar to those of andiroba oil, and C. flexuosa and S. guianensis similar to those of palm oil. FFA compositions from H. tiliaceus, P. caimito, C. flexuosa and S. guianensis are rich in oleic or linoleic acids, which are an important requirement of feedstock for biodiesel production. Some polyphenolic compounds determined by EASI-MS in some of these oils are also known to provide important nutritional and therapeutic benefits to human health. EASI-MS can therefore offer immediate characterization of such oils and help in quality monitoring and control of adulteration and to guide their application in food, cosmetics and the biofuel industries.